1. Field of the Invention
Fiber optic image-transmitting devices with particular reference to apparatus for making axially compressed fiber optic image-inverters having image-receiving and image-emitting opposite end faces, one inverted relative to the other by a 180.degree. axial twist in the bundle between said opposite ends thereof.
2. Description of the Prior Art
Fiber optical image inverters formed by twisting image-transmitting bundles of optical fibers have, heretofore, suffered substantial losses in effective numerical aperture and transmission. This is due to stretching and consequent constriction or tapering of individual fiber elements by amounts which increase from the centermost fibers of the bundle. This reduction in effective numerical aperture and transmission causes vingnetting of images emitted by the twisted bundle.
Efforts to decrease the length of fiber optic image inverters in relation to their diameters increase the relative stretching and optical performance losses so that when space limitations on the use of fiber optic image inverters places a premium on minimum length, a sacrifice in optical performance has been the rule.
According to the present invention, however, optical performance is optimized in fiber optic image inverters of notably shortened over-all lengths.